In the technical field of the present invention, packages essentially consist of at least two liquid containers, such as PET bottles or beverage cans, and a plastic film for packaging and/or holding together groups of liquid containers. The plastic film may additionally be shrunk by a thermal process so that the liquid containers are optimally held together. A thus produced package may be carried by a person at a handle attached to the package. The handle may, for example, be a loop attached to the surface of the shrink package by means of a self-adhesive handle adhesive tape.
Currently, filling systems usually use separate handle application machines for applying the handles to the shrink packages, which apply the handle to the shrunk package downstream of the shrink film machine and the shrink tunnel. One disadvantage thereof is that the shrink package offers little counter-pressure for pressing the self-adhesive handle adhesive tape against it when the handle is applied, particularly if a handle is adhered to the concavity between two liquid containers. A further disadvantage is that the speed of the application head of the handle application machine must be synchronized with the package speed or vice versa. Some space must be provided for the handle application machine within the filling system.
According to some devices and methods known from prior art, the packaging films are initially provided wound up as a roll, such as in European Patent Application EP 0 178 142 A1 and U.S. Pat. No. 6,513,657 B2. Therefore, the films must be unwound for applying the handles, and the handles are then applied to the film. Next, the film, which now includes the handles, is wound up again and supplied to other operations in the filling system. This means that two operations are necessary for winding up and unwinding the film. In addition, there are bulges in the rolls in the wound up state due to the applied handles, which may, on the one hand, result in undesired wear of the film and, on the other hand, makes it difficult to store the rolls of film.
Due to the additional machine element for applying the handles, additional functions are required, such as separating packages that have accumulated one behind the other. Thus the packages are arranged for applying the handles and/or the application head is synchronized with the speed with which the packages are transported through the filling system. These additional functions reduce the overall efficiency of the filling system.
According to various devices and methods known from prior art, packaging films are prepared to include handles before the films are supplied to the packaging device for the packages so that a flexible reaction to different package designs is not possible during the filling operation, if necessary, see, for example, U.S. Pat. No. 6,513,657 B2. In addition, such prepared films are more expensive than non-prepared films.
Various patents of this category for packages having handles and methods for the production thereof are known from prior art and will be described briefly in the following.
European Patent Application EP 0 178 142 A1 discloses a method for packaging liquid containers that includes forming at least one handle. Before the packaging film is heat-shrunk, portions of the film are weakened along central portions of the longitudinal edges of the film such that, as a consequence of heating the film, the weakened portions of the film form openings. The openings are arranged adjacent to the handles so that users may grip the handles through the openings. The handles are pre-applied to the film, i.e. the films are prepared to include handles. The film is unwound for applying the handles and subsequently wound up again. This has a negative effect on the performance of the packaging machine. In addition, the film roll bulges where the handles are applied. There is a risk of jamming during unwinding.
U.S. Pat. No. 3,756,395 discloses a shrink package and a method for the production thereof. Before a plastic film used for the packaging is shrunk, strips are folded locally in some areas of the film within this film, or other types of reinforcing strips are added. The strips may be reinforced by lamination. The strips are applied in areas of the film where a handle is to be provided and where the tension on the film caused by carrying the package is compensated. In this way the shrink package is stabilized.
European Patent Application EP 717 712 B1 discloses multiple packaging for bottles and a method for the production thereof. In a region separating adjacent rows of bottles, a film of heat-shrinkable plastic comprises a series of aligned incisions extending over the whole perimeter of the packaging, which are designed to form a line for detaching each row of bottles from the adjacent row(s) of bottles.
U.S. Pat. No. 6,513,657 B2 discloses a packaging with a handle-forming tear opening. A tearable tape system having a first and a second section is secured to the packaging material. The first section is tearable relative to the second section. The second section remains secured to the packaging material and, in combination with the packaging material, forms a handle. A first slit is formed through the packaging material adjacent a side of the tear opening to allow grasping the handle in the opened state. The handles are pre-applied to the packaging material, i.e. the packaging material is prepared to include handles. In addition, the packaging material is wound up again with the handles applied before the liquid containers are wrapped with the packaging material to form packages.
U.S. Pat. No. 6,354,739 B1 discloses tear control adhesive tapes and containers with a tear control adhesive tape. A container for storing items is provided with a flap of a tear resistant film material with first and second major surfaces for closing the container. A tearable tape strip is located on one of the first and second major surfaces of the flap. A loop-shaped handle is not provided.